1) In computers, the form factor (sometimes hyphenated as form-factor) is the size, configuration, or physical arrangement of a computer hardware object. The term is commonly used in describing the size and/or arrangement of a computer case or chassis or one of its internal components such as a daughterboard . If you see the term applied to software or programming, it will usually mean the size of the program or the amount of memory required to run the program effectively. When used to refer to the size of a free-standing computer or other device, it's close in meaning to footprint .
2) In electric motor terminology, a form factor is the amount of rectified current emitted from a direct current (DC) power source and is expressed as a ratio of the root-mean square (rms) value of the current to the average (av) current or Irms/lav. If the form factor differs much from pure non-pulsating DC (a value of 1.0), it indicates the possibility that motor and brush life will be shorter.